Identification of a new human mtDNA polymorphism (A14290G) in the NADH dehydrogenase subunit 6 gene

Insulin receptor substrate 2 gene Gly1057Asp polymorphism is a risk factor for nonalcoholic fatty liver disease

OBJECTIVE

Nonalcoholic fatty liver disease (NAFLD), which is an emerging global chronic liver disease, has a close association with insulin resistance. We aimed to determine whether the Gly1057Asp (rs1805097) polymorphism of the insulin receptor substrate 2 (IRS2) gene is associated with NAFLD.

METHODS

Using the polymerase chain reaction-restriction fragment length polymorphism method, 135 patients with biopsy-proven NAFLD and 135 controls underwent IRS2 genotype analysis.

RESULTS

Genotype and allele distributions of the IRS2 gene Gly1057Asp variant conformed to the Hardy-Weinberg equilibrium in both the case and control groups (P > .05). The Asp/Asp genotype of IRS2 gene Gly1057Asp polymorphism compared with Gly/Gly genotype was associated with a 2.1-fold increased risk for NAFLD after adjustment for confounding factors (P = .029; odds ratio = 2.10, 95% CI = 1.23-3.97).

CONCLUSION

Our findings revealed for the first time that the Gly1057Asp Asp/Asp genotype of the IRS2 gene is a marker of increased NAFLD susceptibility; however, studies in other populations are required to confirm the results.

RESISTIN GENE POLYMORPHISM AND NONALCOHOLIC FATTY LIVER DISEASE RISK

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is a chronic liver disease and one of the main global health issues in which liver fat surpasses 5% of hepatocytes without the secondary causes of lipid accumulation or excessive alcohol consumption. Owing to the link between NAFLD and insulin resistance (IR) and obesity and the role of resistin in theses metabolic disorders, we explored the possible association between resistin gene (RETN) variant and NAFLD.

METHODS

A total of 308 unrelated subjects, including 152 patients with biopsy-proven NAFLD and 156 controls were enrolled and genotyped for the RETN gene rs3745367 variant using PCR-RFLP method.

RESULTS

NAFLD patients had higher liver enzymes, systolic blood pressure (SBP), and diastolic blood pressure (DBP) than the controls (P<0.001). However, we observed no significant difference in genotype and allele frequencies between the cases with NAFLD and the controls for the RETN rs3745367 polymorphism either before or after adjustment for confounding factors including age, BMI, sex, smoking status, SBP, and DBP.

CONCLUSION

To our knowledge, this study is the first one that investigated the association between RETN gene rs3745367 variant and biopsy-proven NAFLD. Our findings do not support a role for this gene polymorphism in NAFLD risk in Iranian population; nonetheless, they need to be further investigated in other populations.

Emerging role of tumor-related functional peptides encoded by lncRNA and circRNA

Non-coding RNAs do not encode proteins and regulate various oncological processes. They are also important potential cancer diagnostic and prognostic biomarkers. Bioinformatics and translation omics have begun to elucidate the roles and modes of action of the functional peptides encoded by ncRNA. Here, recent advances in long non-coding RNA (lncRNA) and circular RNA (circRNA)-encoded small peptides are compiled and synthesized. We introduce both the computational and analytical methods used to forecast prospective ncRNAs encoding oncologically functional oligopeptides. We also present numerous specific lncRNA and circRNA-encoded proteins and their cancer-promoting or cancer-inhibiting molecular mechanisms. This information may expedite the discovery, development, and optimization of novel and efficacious cancer diagnostic, therapeutic, and prognostic protein-based tools derived from non-coding RNAs. The role of ncRNA-encoding functional peptides has promising application perspectives and potential challenges in cancer research. The aim of this review is to provide a theoretical basis and relevant references, which may promote the discovery of more functional peptides encoded by ncRNAs, and further develop novel anticancer therapeutic targets, as well as diagnostic and prognostic cancer markers.

Fifteen novel mutations in the mitochondrial NADH dehydrogenase subunit 1, 2, 3, 4, 4L, 5 and 6 genes from Iranian patients with Leber's hereditary optic neuropathy (LHON)

Leber's hereditary optic neuropathy (LHON) is an optic nerve dysfunction resulting from mutations in mitochondrial DNA (mtDNA), which is transmitted in a maternal pattern of inheritance. It is caused by three primary point mutations: G11778A, G3460A and T14484C; in the mitochondrial genome. These mutations are sufficient to induce the disease, accounting for the majority of LHON cases, and affect genes that encode for the different subunits of mitochondrial complexes I and III of the mitochondrial respiratory chain. Other mutations are secondary mutations associated with the primary mutations. The purpose of this study was to determine MT-ND variations in Iranian patients with LHON. In order to determine the prevalence and distribution of mitochondrial mutations in the LHON patients, their DNA was studied using PCR and DNA sequencing analysis. Sequencing of MT-ND genes from 35 LHON patients revealed a total of 44 nucleotide variations, in which fifteen novel variations-A14020G, A13663G, C10399T, C4932A, C3893G, C10557A, C12012A, C13934T, G4596A, T12851A, T4539A, T4941A, T13255A, T14353C and del A 4513-were observed in 27 LHON patients. However, eight patients showed no variation in the ND genes. These mutations contribute to the current database of mtDNA polymorphisms in LHON patients and may facilitate the definition of disease-related mutations in human mtDNA. This research may help to understand the disease mechanism and open up new diagnostic opportunities for LHON.

Accumulation of mitochondrial genome variations in Persian LQTS patients: a possible risk factor?

BACKGROUND

Long QT syndrome (LQTS) is among arrhythmia disorders of the heart that causes sudden cardiac death in young individuals. As yet, most of investigations have focused on nuclear genome for finding genetic defects in this disorder, but some of the cases with LQTS cannot be explained by mutations of identified genes. On the other hand, it has been reported that the activity of ion channels in cardiomyocytes is sensitive to ATP level. It prompted us to focus on the mitochondrial DNA and monitor the point mutations of genome which are probably the cause of respiratory chain defects and reduced ATP generation.

METHODS

We searched about 55% of the mitochondrial DNA (mtDNA) by temporal temperature gradient gel electrophoresis (TTGE), and DNA fragments showing abnormal banding patterns were sequenced for identification of exact mutations.

RESULTS

In 39 patients (33 familial and 6 sporadic cases), for the first time, we detected 35 mtDNA mutations in which 8 were novel (23%) and 27 (77%) have been reported in other mitochondrial diseases. Our results showed that these mutations in LQTS patients were higher than those in normal controls (P<.0001), and the number of mutations in LQTS patients with syncope is higher than in patients without syncope (P<.001).

CONCLUSIONS

As the mitochondrion's ATP synthesis is important in heart, it is possible that mutations and their accumulation in mtDNA could constitute a predisposing factor that in combination with environmental factors may trigger the syncope in patients with LQTS.